An array substrate is an important component of a display device, and includes at least a data line, a gate line, a thin film transistor and a pixel electrode. FIG. 1 illustrates a conventional thin film transistor, including a source 1, a drain 2, a gate 3 and an active layer 4. The data line is connected to the source 1 of the thin film transistor, the gate line 5 is connected to the gate 3 of the thin film transistor, the drain 2 is connected to the pixel electrode 6, and the pixel electrode 6 is charged by the thin film transistor. The stronger charging capability the thin film transistor has, the shorter charging time becomes, and thereby the better display effect is obtained.
With people's increasing demand on display quality of the display device, the number of pixel units in the array substrate is required to be increased, so as to improve the resolution of the display device. The larger the number of the pixel units is, the longer the charging time becomes. Consequently, the charging efficiency of the thin film transistor is increasingly required to be improved, and the charging time of the thin film transistor is increasingly required to be reduced.